Perhaps all of this is related to the Carolina Event ... a series of large craters that stretches south to north - larger to smaller.
The postulated Younger Dryas strike hit on the glacier somewhere in Canada. There would be little debris as the 2 mile thick glacier cap would have absorbed most of the material before beginning to melt.
A friend of mine has a brother who lives in Martha's Vineyard. He says that one of his metal detector friends has a pickup truck full of it and fishermen complain about it screwing up their nets.
Don’t forget, the sea level was a few hundred feet below where it is today because there was so much ice on the land.